Allow to change the workspace

So, I really do not like to have this `Sites` directory at my root drive. Then I made this for allow to configure the my home workspace setting an environment variable.

The PR is a very alpha version, my plan was to make this:

- [x] Make the `setup_environment` batch redirect to the folder assigned to the `RAILS_WORKSPACE` environment variable.
- [ ] An option to set the workspace at the installation.
- [ ] The docs.

So, I opened it to discuss with you guys what you think the
1. I would use `MD` and `CD` to the next line.
2. The check checks for `%RAILS_WORKSPACE%` but the mkdir command creates a directory named `%RAILS_WORKSPACE%.` (notice the dot)